Automatic air shutoff and draft control for oil burners



M/HAMMELL 2,459,815

K. AUTOMATIC AIR SHUTOFF AND DRAFT CONTROL FOR OIL BURNERS Filed Jan. 23, 1947 Jan. 25, 1949.

INVENTOR. Kenna M. Hmneu.

,4 7' TORNEV Patented Jan. 25, 1949 AUTOMATIC AIR SHUTOFF AND DRAFT CONTROL FOR OIL BURNEBS Kemper M..Hammell, Bloomington, 111., 'assignor to Eureka Williams Corporation, Detroit, Mich, a corporation of Michigan Application January 23, 1947, Serial No. 723,857

1 11 Claims.

This invention relates to off and draft control for oil burners which will automatically shut off the air passage to the fan in an oil burner when the fan'stops, thus keeping the furnace from being cooled down by room air which would otherwise be inducted through the furnace due to the draft effected by the hot stack.

While devices of this type have heretofore been suggested, such devices have not proven" to be entirely satisfactory due to the expensive construction thereof or the lack of dependability thereof in operation. The present invention contemplates not only an automatic air shutoff for oil burners but also one which will function as a draft control for the fan during the operation thereof.

A principal object of the invention therefore is to provide a new and improved automatic air shutoff for oil burners. 4

Another object of the invention is to provide a new and improved draft control for oil burners.

Another objectof the invention is to provide a new and improved automatic air shutoff and draft control for oil burners.

Other objects and advantages of the invention will be apparent from a consideration of the following specification taken in conjunction with the accompanying drawing, of which there is one sheet.

In the drawings:

Fig. 1 is an elevational view of an oil burner embodying the invention;

Fig. 2 is an enlarged fragmentary sectional view of the air shutoff and draft control in one position thereof during operation of the fan;

Fig. 3 is a view similar to Fig. 1 but showing the position of the parts when the fan is stopped; and

Fig. 4 is a sectional view partly broken away taken along the line 4-4 of Fig. 3.

As illustrated in the embodiment of the invention selected for purposes of illustration, an automatic air shutoff and draft control comprises an oil burner housing l formed at one end thereof to define a fan case i2 having an air inlet l4. A hollow cup shaped blower wheel I8 is arranged 'within the fan chamber l8 defined by the case 12 andadjacent the inlet l4 with the interior of the blower wheel i facing the inlet and arranged in alignment therewith. The oil burner includes .an electric motor having a shaft 22 upon which the wheel itis mounted for rotation. A valve member comprising a plate or sliding air cone an automatic air shut- 2 24 is arranged within the wheel l6 normal to the shaft 22.

A plurality of extensible linkage assemblies indicated generally at 26 is connected to said valve member and to said wheel so as to support the valve member for movement axially of the wheel I6 and shaft 22.

The valve member in one position thereof, as illustrated in Fig. 3, is arranged to obstruct the air inlet l4 so as to shut off the flow of air into the fan case and in another position thereof, as illustrated in Fig. 2, is spaced from the inlet and arranged within the wheel l6 so as to permit the flow of air through said inlet i4 into the blower wheel 16. The motor 20 is arranged for rotating the blower wheel. During rotation thereof the blower wheel is effective for circulating air through the housing III to the combustion chamber of the furnace with which the oil burner is associated for mixture with the oil fog which is discharged by the nozzle 30 into the combustion chamber.

The oil burner may be of the construction disclosed and claimed in the application for United States Letters Patent filed by myself and Robert R. Witherell on November 15, 1946, Serial No. 709,970. A coil spring 32 arranged between the hub 34 of the wheel l6 and the valve member 24- is operative for biasing the valve member 24 to its closed position as illustrated in Fig. 3 so that upon discontinuance of rotation of the blower wheel the valve will automatically close the inlet there- One of the rings 36 of the wheel it forms a seat or stop for the rim of the valve member 24 so as to limit the movement of the valve member 24 in one direction under the influence of the spring 22. The valve member is provided with a bushing 38 at its center which has a screw 42 threadedly arranged therein. One end of the screw 40 is engageable with the shaft 22 so as to form a stop for determining the open position of the valve member as shown in Fig. 2. The exposed end of the screw is provided with-a kerf so that a tool may be applied thereto for axially shifting the position of the screw relative to the bushing 28 whereby the open position of the valve member 24 may be shifted to a position other than that shown at Fig. 2. In other words, as shown in Fig. 2, the valve member 24 is positioned so that it does not cut off to any appreciable extent the flow of alrto any portion of the blades 42 of the wheel l6. However, by shifting the screw 40 axially to the right the valvemember 24 may be stopped in its open position so as to cut down the effective axial length of the blades 42, thereby cutting down the capacity of the blower wheel I or in effect axially reducing the length of the blower wheel. In this manner the capacity of the blower wheel l6 may be accurately adjusted. The screw 40 thus forms an adjustable stop for limiting movement of the valve member 24 in one direction or for determining the open position thereof.

Each of the linkage assemblies 26 comprises a series of pivotally connected links or arms, one end of each of which is pivoted at 50 to a bracket 52 carried by the rear wall 84 of. the blower wheel. The other end of each of the linkage assemblies is pivoted at 56 to a bracket 58 carried by the valve member 24. The mass of the linkage assembly and the arrangement thereof is such that centrifugal force of the linkage assembly during the rotation of the blower wheel ii at the speed at which it is driven by the motor 20 will cause the linkageassemblies 26 and thevalve member N to assume the position as illustrated in Fig. 2 and as determined by the screw 40. The valve member 24 is generally bell shaped, with the apex thereof arranged at the center of rotation. of the fan and pointing outwardly from the inlet opening I so as to help guide the air through the inlet ll to the blades 42 of the fan. The air discharged by the blower wheel it flows from the chamber 18 lengthwise of the housing l and around the motor 20. While the fan illustrated employs an axial type fan housing, the invention will work as well in a scroll shaped fan housing.

While I have illustrated and described a preferred embodiment of my invention, it is understood that this is capable of modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. An automatic air shutofi for oil burners comprising a fan case having an air inlet, a hollow cup shaped blower wheel arranged within said case adjacent said inlet with the interior of said wheel facing said inlet and arranged in alignment therewith, a rotatable drive shaft upon which said wheel is mounted for rotation, a valve member comprising a plate arranged within said wheel normal to said shaft, extensiblelinkage connected to said plate and to said wheel so as to support said plate for movement axially of said blower wheel and to rotate with said shaft, said plate in one position thereof being arranged to obstruct said inlet so as to shut ofi the flow of air through said fan case and in another position thereof being spaced from said inlet and arranged within said wheel so as to permit the flow of air through said inlet, a motor connected .to said shaft for rotating said blower wheel, said linkage being centrifugally operable upon rotation of said wheel to actuate the same so as to shift said plate to said other position, and spring means arranged to bias said plate to said one position thereof so that upon discontinuance of rotation of said blower wheel said plate will automatically close said inlet thereto, said fan case having an outlet.

2. An automatic air shutoff and draft control for oil burners according to claim 1 wherein an adjustable stop determines said other position of said plate so as to regulate the effective axial length of said blower wheel.

3. An automatic air shutoff for oil burners according to claim 1 wherein said plate is generally a valve member comprising a plate arranged normal to said shaft and within said wheel, extensible linkage. connected to and arranged between said plate and to said wheel so as to support said plate for movement axially of said wheel so as to increase or decrease the effective axial length of said blower wheel, said plate in one position thereof being arranged to obstruct said inlet so as to shut off the flow of air through said fan case and in another position thereof being spaced from said inlet and arranged so as to permit the flow of air through said inlet, said linkage being centrifugally operable upon rotation of said wheel to actuate the same so as to.

shift said plate to said other position, and spring means arranged to bias said plate to said one position thereof so that upon discontinuance of rotation of said blower wheel said plate will automatically close said inlet thereto.

5. An automatic air shutoff according to claim 4 wherein said plate is provided with an adjustable stop for determining said other of its positions relative to said inlet so as to reduce the effective axial length of said blower wheel and shut off the flow of air to one portion thereof without interfering with the flow of air to the remaining portion thereof.

6. An automatic air shutoff according to claim 4 wherein said plate is generally bell-shaped with the apex thereof projecting axially through said inlet and wherein said linkage is partially nested in said plate when said plate is in said other position.

7. An automatic air shutoff comprising a fan case having an air inlet, a hollow cup shaped blower wheel rotatably arranged within said case, a rotatable valve member within and movable axially relative to said blower wheel and in one position thereof being arranged to obstruct said inlet so as to shut off the flow of air through said fan case and in another position thereof being arranged so as to permit the flow of air through said inlet, means operable upon rotation of said wheel for moving said valve member to said other position for opening said inlet, and spring means arranged to bias said valve member to said one position thereof so that upon discontinuance of rotation of said blower wheel said valve member will automatically close said inlet thereto.

8. An automatic air shutoff according to claim 7 wherein said valve member is provided with an adjustable member which determines said other position of said valve member and the effective axial length of said wheel.

9. In a blower, a fan case having an airinlet, a blower wheel rotatably arranged within said case, a movable valve member arranged within said wheel and operable for closing and opening said inlet, means mounting said valve member for movement relative to said inlet and said blower wheel, said valve member in one position thereof being arranged to obstruct said inlet so as to shut off the flow of air through said fan case and in another position thereof so as to permit the flow of air through said inlet, centrifugally responsive means operable upon rotation of said shaft for moving said valve member to said other position for opening said inlet, and spring means arranged to bias said valve member to said one position upon discontinuance of rotation of said fan, said valve member being generally bell shaped and arranged so as to direct the air which flows axially into said blower wheel radially outwardly toward the blades of said blower wheel.

10. An automatic air shutoff and draft control for oil burners comprising a fan case having an air inlet, a fan rotatably arranged within said case, a movable valve member arranged for movement axially of said inlet and rotatable with said fan, said valve member in one position thereof being arranged to obstruct said inlet so as to shut off the flow of air through said fan case and in another position thereof being spaced from said inlet and arranged so as to permit the flow of air through said inlet, means operable upon rotation of said fan to shift said valve member to said other position, and spring means arranged to bias said valve member to said one position thereof so that upon discontinuance of rotation of said fan said valve member will automatically close said inlet thereto, said fan case having an outlet, said valve member being in nested relation with said fan and said means being shielded from the air through said fan by said valve member.

11. In ablower wheel having axially extending blades and which wheel is closed on one side, said wheel having at its other side a ring forming an end of said wheel and an opening through which air flows into said wheel, an air deflecting circular member comprising a plate arranged within said wheel normal to the axis of rotation thereof and extending into close proximity to said blades and means for mounting said member for rotation with and adjustment axially of said wheel so that said member may be positioned to shut ofi the flow of air to those portions of said blades adjacent the closed side of said wheel whereby to decrease the effective axial length of said wheel, said plate being shaped so as to have a central apex projecting away from the closed end of said wheel and arranged so as to direct the air, which flows axially into said blower wheel through said opening, radially outwardly toward the blades of said blower wheel, the diameter of said member being greater than the diameter of said opening in said ring but less than the diameter inside said wheel between the inner edges of said blades, and screw threaded means operable for adjusting said member axially of said wheel.

REFERENCES CITED The following references are of record in the file of this patent:

- UNITED STATES PATENTS Number Name Date 1,603,955 Johnson Oct. 19, 1926 1,834,959 Ma Dec. 8, 1931 2,351,878 Russel June 20, 1944 2,373,166 Chapman et a1. Apr. 10, 1945 FOREIGN PATENTS Number Country Date 165,930 Switzerland Feb. 16, 1934 710,215 France -4--- Aug. 20, 1931 

